Line-end extension method and device

ABSTRACT

Methods of forming line-end extensions and devices having line-end extensions are provided. In some embodiments, a method includes forming a patterned photoresist on a first region of a hard mask layer. A line-end extension region is formed in the hard mask layer. The line-end extension region extends laterally outward from an end of the first region of the hard mask layer. The line-end extension region may be formed by changing a physical property of the hard mask layer at the line-end extension region.

BACKGROUND

Advances in the manufacture of semiconductor integrated circuits (ICs)have led to increases in functional density (i.e., the number ofinterconnected devices per chip area) as well as decreases in geometrysize (i.e., the smallest component (or line) that can be created using afabrication process). Increasing functional density while decreasinggeometry size generally provides benefits by increasing productionefficiency and lowering associated costs. However, such advances interms of size and density of devices or components have also beenaccompanied by increased complexity in design and manufacturing ofdevices incorporating these ICs.

For example, reducing sizes and spacing between ICs features defined andformed on a semiconductor substrate generally includes using a pluralityof different photolithographic masks, and cut processes are performed toyield patterned features utilized in the IC.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1 through 8 are schematic views illustrating a method offabricating an integrated circuit in accordance with some embodiments ofthe present disclosure.

FIG. 9 is a schematic diagram illustrating a patterned feature formed bya modification of the method described with respect to FIGS. 1 through 8, in accordance with some embodiments.

FIG. 10 is a plan view diagram illustrating a device, in accordance withsome embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Reference throughout the specification to deposition techniques fordepositing dielectric layers, metals, or any other materials includessuch processes as chemical vapor deposition (CVD), low-pressure chemicalvapor deposition (LPCVD), metal organic chemical vapor deposition(MOCVD), plasma-enhanced chemical vapor deposition (PECVD), plasma vapordeposition (PVD), atomic layer deposition (ALD), molecular beam epitaxy(MBE), electroplating, electro-less plating, and the like. Specificembodiments are described herein with reference to examples of suchprocesses. However, the present disclosure and the reference to certaindeposition techniques should not be limited to those described.

Reference throughout the specification to etching techniques forselective removal of semiconductor materials, dielectric materials,metals, or any other materials includes such processes as dry etching,wet chemical etching, reactive ion (plasma) etching (RIE), washing, wetcleaning, pre-cleaning, spray cleaning, chemical-mechanicalplanarization (CMP) and the like. Specific embodiments are describedherein with reference to examples of such processes. However, thepresent disclosure and the reference to certain etching techniquesshould not be limited to those described.

As the sizes or dimensions of features formed in integrated circuitsdecrease, a spacing, distance, or gap between ends of adjacent featuresmay be constrained by limits of the processing steps utilized to formthe features. For example, photolithographic and cutting processes usedto manufacture patterned features of an integrated circuit may havelower limits in terms of spacing between features that can practicallybe achieved. These lower limits may be defined, for example, bydimensions of a photomask that can be physically produced based on thelayout for the integrated circuit.

As described herein, the present disclosure provides methods and devicesin which line-end extensions of patterned features are formed at the endof feature lines, thereby facilitating a reduction in the distance orgap that may be achieved between patterned features of an integratedcircuit. In some embodiments, the line-end extensions may be formedwithout additional cut layers (and corresponding additional maskprocesses), which otherwise may be relied on to form line-end extensionsin other techniques.

In view of the foregoing, various embodiments of the present applicationare directed towards methods and devices in which line-end extensionregions are formed in a hard mask layer by directed bombardment of ionbeams. The ion beams may be at least partially blocked from reachingline-end extension regions of the hard mask layer. The line-endextension regions may be regions which extend laterally outward fromends of a patterned photoresist on the hard mask layer, and thepatterned photoresist blocks at least some of the ion beams fromreaching the line-end extension regions. For example, the line-endextension regions may be shadow regions which receive a lowerconcentration or less of the ions than other regions of the hard masklayer. The ions may change a physical property of the hard mask layer,such as a selectivity to an etchant. As such, the unblocked regions ofthe hard mask layer may be readily removed by an etchant, while theline-end extension regions (as well as regions which were covered by thepatterned photoresist) of the hard mask layer may be retained and usedto pattern a target layer. Patterned features may thus be formed in aself-aligned manner in which the patterned features include regionscorresponding to the line-end extension regions of the hard mask layer.This facilitates a significant reduction in a gap between patternedfeatures that may be achieved.

FIGS. 1 through 8 are cross-sectional views illustrating a method offabricating an integrated circuit in accordance with one or moreembodiments of the present disclosure. Additional steps can be providedbefore, during, and after the method, and some of the steps describedcan be replaced or eliminated for other embodiments of the method.

As shown in FIG. 1 , a hard mask 14 is formed on a target layer 12. Thehard mask 14 may be any suitable hard mask including a masking materialused to protect underlying regions (e.g., of the target layer 12) duringprocessing. Suitable materials for the hard mask 14 may includedielectric materials (e.g., semiconductor oxides, semiconductornitrides, semiconductor oxynitrides, semiconductor carbides, metaloxides, other metal compounds, etc.), metals, metal alloys, polysilicon,and/or other suitable materials. In some embodiments, the hard mask 14is a silicon nitride film.

The hard mask 14 may be formed by any suitable process, including, forexample, deposition, anodization, thermal oxidation, or the like. Insome embodiments, the hard mask 14 is formed by a deposition process.The deposition process may be any suitable deposition process fordepositing a hard mask layer, including, for example, chemical vapordeposition (CVD), low-pressure chemical vapor deposition (LPCVD),plasma-enhanced chemical vapor deposition (PECVD), plasma vapordeposition (PVD), atomic layer deposition (ALD), or the like.

The target layer 12 is formed on a substrate 10. The substrate 10 may beany suitable substrate, such as any suitable semiconductor substrate. Invarious embodiments, the substrate 10 may be formed of a crystallinesemiconductor material, for example, monocrystalline silicon,polycrystalline silicon, or some other type of crystalline semiconductormaterial. In some embodiments, the substrate 10 is a silicon substrate;however, embodiments provided herein are not limited thereto. Forexample, in various embodiments, the substrate 10 may include galliumarsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC), or anyother semiconductor material. The substrate 10 may include variousdoping configurations depending on design specifications. In someembodiments, the substrate 10 is a p-type substrate having aconcentration of p-type dopants. In other embodiments, the substrate 10is a n-type substrate having a concentration of n-type dopants.

In various embodiments, the substrate 10 may have a substantiallyuniform composition or may include various layers. The layers may havesimilar or different compositions, and in some embodiments, somesubstrate layers have non-uniform compositions to induce device strainand thereby tune device performance. Examples of layered substratesinclude silicon-on-insulator (SOI) substrates. In some embodiments, alayer of the substrate 10 may include an insulator such as asemiconductor oxide, a semiconductor nitride, a semiconductoroxynitride, a semiconductor carbide, and/or other suitable insulatormaterials.

The target layer 12 may be a layer of any material that is to bepatterned to form one or more features of an integrated circuit.Line-end extensions are formed in or by the target layer 12, as will bediscussed in further detail herein. In some embodiments, the targetlayer 12 may be a dielectric layer, such as a dielectric layer formed ofor including oxide, nitride, silicon oxide (SiO_(x)), silicon oxynitride(SiON), silicon nitride (SiN), or the like. In some embodiments, thetarget layer 12 may be a semiconductor layer, such as silicon (Si),gallium arsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC),or any other semiconductor material. In some embodiments, the targetlayer 12 may be an electrically conductive layer, such as a layer ofcopper (Cu), or any other metal or electrically conductive material. Thematerials utilized for the target layer 12 may be selected as desireddepending, for example, on the particular features to be formed by thetarget layer 12 once it is patterned. In various embodiments, thefeatures formed by the target layer 12 may include, for example,semiconductor fins for a FinFET device, gate features, conductive tracesor vias, or any other features of an integrated circuit.

The target layer 12 may be formed by any suitable process, including,for example, depositing dielectric layers, metals, or any othermaterials includes such processes as chemical vapor deposition (CVD),low-pressure chemical vapor deposition (LPCVD), metal organic chemicalvapor deposition (MOCVD), plasma-enhanced chemical vapor deposition(PECVD), plasma vapor deposition (PVD), atomic layer deposition (ALD),molecular beam epitaxy (MBE), electroplating, electro-less plating, orthe like.

As shown in FIG. 2 , a photoresist 16 is patterned on the hardmask 14,for example, using a lithographic exposure in which a photomask is usedto expose selected regions of the photoresist 16 to radiation. Theexposure causes a chemical reaction to occur in the exposed regions ofthe photoresist 16. After exposure, a developer is applied to thephotoresist 16. The developer dissolves or otherwise removes either theexposed regions in the case of a positive resist development process orthe unexposed regions in the case of a negative resist developmentprocess. Suitable positive developers include TMAH (tetramethyl ammoniumhydroxide), KOH, and NaOH, and suitable negative developers includesolvents such as n-butyl acetate, ethanol, hexane, benzene, and toluene.In various embodiments, the patterned photoresist 16 which remains afterthe development process has a shape substantially corresponding of ashape of the feature to be defined in the target layer 12. However, theends of the features to be defined in the target layer 12 (e.g., theline-ends) will be extended laterally beyond the ends of the patternedphotoresist 16.

Ions 20 are implanted into the hard mask 14, as shown in FIG. 2 .Implantation of the ions 20, e.g., by ion bombardment, causes a changein one or more properties of regions of the hard mask 14 into which theions 20 are implanted. In some embodiments, the implanted ions 20 change(e.g., increase) a selective etch rate of the hard mask 14 when exposedto a suitable etchant. In some embodiments, the ions 20 include or areformed from an element chosen from the group including nitrogen (N),tellurium (Te), boron (B), gallium (Ga), phosphorus (P), arsenic (As),argon (Ar), krypton (Kr), and xenon (Xe).

The ions 20 are implanted into the hard mask 14 and may be directionallyimplanted, for example, by ion beams which are irradiated at selectedangles with respect to the hard mask 14. In some embodiments, the ions20 are directed toward the hard mask 14 by ion beams that arenon-orthogonal with respect to the hard mask 14. For example, in someembodiments, the ions 20 are irradiated toward the hard mask 14 at anion beam angle θ with respect to a direction 22 that is orthogonal tothe hard mask 14. In the example shown in FIG. 2, ion beams may beprovided at the ion beam angle θ originating from two differentdirections (e.g., from right-to-left and from left-to-right as shown inFIG. 2 ).

As shown in FIG. 2 , bombardment or implantation of ions 20 into thehard mask 14 forms a first region 31 of full ion bombardment, and secondregions 32 of partial ion bombardment. The second regions 32 of the hardmask 14 are only partially bombarded by the ions 20, since thephotoresist 16 blocks at least some of the directional ion beams fromreaching the second regions 32 of the hard mask 14. That is, the secondregions 32 may be shadow regions or regions of the hard mask 14 whichare shielded from receiving all of the directional ion beams due to thepresence of the photoresist 16. In some embodiments, the first region 31of the hard mask 14 may be completely unprotected or otherwise shieldedfrom receiving the ion beams, and thus the first region 31 may bereferred to as receiving 100% bombardment of the ions 20. The secondregions 32 may receive any partial bombardment of the ions 20, such as90% or less, 75% or less, 50% or less, or 25% or less of the bombardmentof the ions 20. The amount or percentage of bombardment of the ions 20received at the second regions 32 should be less than the amount orpercentage of bombardments of the ions 20 received at the first region31, so that one or more properties of the first region 31 are changedwith respect to the second regions 32, which as will be discussed laterherein, may include a change in the selectivity to an etchant. Forexample, by receiving less than full bombardment (such as less than 90%,less than 75%, less than 50%, or less than 25%), the second regions 32may be less readily removed by an etchant than the first region 31 whichreceives 100% bombardment of the ions 20. Other factors may impact thechange in selectivity to an etchant based on a reduced or partialbombardment of ions 20, including, for example, the material of the hardmask 14, the ion species, the etchant used, and the like. In someembodiments, receiving partial bombardment of the ions 20, such as 90%or less, 75% or less, 50% or less, or 25% or less, facilitates anappreciable difference in properties between the second regions 32 andthe first region 31 (which receives 100% bombardment) so that the firstregion 31 may be readily removed (e.g., by an etchant) while the secondregions 32 are at least partially retained.

In some embodiments, as shown in FIG. 2 , the second regions 32 may bereferred to as receiving 50% bombardment of the ions 20, as each of thesecond regions 32 receives ions 20 from only one ion beam of aparticular direction (e.g., from right-to-left and from left-to-right asshown in FIG. 2 ), while ions 20 from the other ion beam is blocked bythe photoresist 16. The second regions 32 may be referred to herein asline-end extension regions 32, as these regions will be effective extendthe line-ends of the features formed in the target layer 12, as will bedescribed in further detail later herein.

The line-end extension regions 32 may have a length L1 (e.g., in thehorizontal direction as shown in FIG. 2 ) that is dependent on the ionbeam angle θ and the height h of the photoresist 16. In someembodiments, the length L1 of the line-end extension regions 32 may beprovided by the following equation:L1=h×tan θ

Accordingly, the line-end extension regions 32 may be formed to have anydesirable length L1, for example, by selectively forming the height h ofthe photoresist 16 at a height suitable to form the desired length L1 ofthe line-end extension regions 32 and/or by selectively irradiating thehard mask 14 with ion beams having a particular ion beam angle θsuitable to form the desired length L1 of the line-end extension regions32. A region underlying the photoresist 16 may have a length L2 of anydesired length, depending upon a desired feature length of a patternedfeature to be formed according to the method illustrated herein. Thetotal length of the patterned feature to be formed may be equal to thelength L2 plus two times the length L1 of the line-end extension regions32.

In some embodiments, the photoresist 16 has a thickness or height h thatis less than 100 nm. In some embodiments, the photoresist 16 has aheight h that is less than 75 nm. In some embodiments, the photoresist16 has a height h that is within a range from about 20 nm to about 50nm.

In some embodiments, the hard mask 14 has a thickness that is less than100 nm. In some embodiments, the hard mask 14 has a thickness that isless than 50 nm. In some embodiments, the hard mask 14 has a thicknessthat is within a range from about 10 nm to about 20 nm.

In some embodiments, the target layer 12 has a thickness that is lessthan 100 nm. In some embodiments, the target layer 12 has a thicknessthat is less than 50 nm. In some embodiments, the target layer 12 has athickness that is within a range from about 20 nm to about 35 nm.

In some embodiments, the ion beam angle θ is less than about 85°. Insome embodiments, the ion beam angle θ is less than 80°. In someembodiments, the ion beam angle θ is greater than 30°. In someembodiments, the ion beam angle θ is within a range from about 30° toabout 85°. In some embodiments, the ion beam angle θ is within a rangefrom about 50° to about 80°. As discussed above, the length L1 of theline-end extension regions 32 depends at least in part on the height hof the photoresist 16 and the ion beam angle θ. By irradiating the ions20 at an ion beam angle θ is within a range from about 30° to about 85°,the line-end extension regions 32 may be formed to have a suitablelength L1 and the ions 20 may be effectively implanted into the hardmask 14. Outside of the ranges described herein, the ions 20 may not beeffectively implanted into the hard mask 14 which may result in aninsufficient change of the one or more properties of the first region 31of the hard mask 14. For example, by irradiating the ions 20 at an ionbeam angle θ that is less than about 30°, the first region 31 may notreceive implanted ions 20 suitable to alter the selectivity of the firstregion 31 to an etchant. On the other hand, by irradiating the ions 20at an ion beam angle θ that is greater than about 85°, the length L1 ofthe line-end extension regions 32 may be limited, as the photoresist 16would need a height h that is relatively high in order to provide adesired length L1 of the line-end extension regions 32.

The implantation of ions 20 into the hard mask 14 changes one or morephysical properties of the hard mask 14. In some embodiments, theimplantation of ions 20 into the first region 31 of the hard mask 14reduces the resistance to etching of the first region 31 so the firstregion 31 of the hard mask 14 may be more readily removed by an etchingprocess than portions of the hard mask 14 which are not irradiated withions 20 or which receive a lesser percentage of bombardment of ions 20.That is, the first region 31 may be more readily removed by etching thanthe second regions or line-end extension regions 32.

In some embodiments, the ions 20 are implanted with suitable energy sothat the ions 20 penetrate at least halfway into the hard mask 14. Insome embodiments, the ions 20 are implanted with an energy of 25 keV to250 keV. In some embodiments, the ions 20 are implanted in the firstregion 31 with a concentration of about 10¹² to 10¹⁵ ions/cm², while theions 20 are implanted in the line-end extension regions 32 with aconcentration that is less than the concentration of ions 20 implantedin the first region 31. In some embodiments, the ions 20 are implantedin the line-end extension regions 32 with a concentration that is lessthan 25% than the concentration of ions 20 that are implanted in thefirst region 31. In some embodiments, the ions 20 are implanted in theline-end extension regions 32 with a concentration that is less than 50%than the concentration of ions 20 that are implanted in the first region31. In some embodiments, the ions 20 are implanted in the line-endextension regions 32 with a concentration that is less than 75% than theconcentration of ions 20 that are implanted in the first region 31. Theconcentration of ions 20 implanted in the first region 31 and in theline-end extension regions 32 may be selected depending on variousfactors, including, for example, a desired change in property (e.g.,etchant rate) of the hard mask layer 14 at the line-end extensionregions 32 as compared to the first region 31.

A ratio r1/r2 of the etching rates at which the first region 31 and thesecond regions or line-end extension regions 32 of the hard mask 14,respectively, are etched may be selected as desired, for example,depending on design considerations. In some embodiments, the ratio ofetching rates may be dependent at least in part on various factors, suchas the species of the ions 20, the duration of ion bombardment, theconcentration of the ions 20 during ion bombardment, the etchant used,or various other factors. In some embodiments, the ratio of etchingrates r1/r2 may be greater than 1.5, greater than 2.0, greater than 3.0,or greater than 5.0.

As shown in FIG. 3 , the photoresist 16 is removed subsequent to the ionbombardment of the hard mask 14. The photoresist 16 may be removed byany suitable technique. In some embodiments, the photoresist 16 isremoved by a wet etching process. The photoresist 16 may be removed, insome embodiments, by any photoresist stripping technique utilizing anyorganic stripping, inorganic stripping, or dry stripping chemicals toremove the photoresist 16.

Once the photoresist 16 has been removed, a non-bombarded region 33 ofthe hard mask 14 is exposed. The non-bombarded region 33 is a regionunderlying the position at which the photoresist 16 was present, and thephotoresist 16 blocked the ions 20 from reaching the non-bombardedregion 33. Thus, the non-bombarded region 33 may have a greaterresistivity to etching than the first region 31 of the hard mask 14. Insome embodiments, the non-bombarded region 33 may have a greaterresistivity to etching than the line-end extension regions 32 of thehard mask 14.

As shown in FIG. 4 , the first region 31 of the hard mask 14 is removed.The first region 31 of the hard mask 14 may be removed by any suitabletechnique, including, for example, by wet etching, dry etching, ReactiveIon Etching (RIE), ashing, or any other suitable etching methods. Insome embodiments, the first region 31 of the hard mask 14 is removed bya first etchant gas 42 having an etchant chemistry with a highselectivity to the first region 31. For example, an etchant gas may beutilized which removes the first region 31 at a higher etching rate thanit removes the line-end extension regions 32 and the non-bombardedregion 33 of the hard mask 14. In some embodiments, the first region 31of the hard mask 14 is removed by an etchant gas including carbontetrafluoride (CF₄), difluoromethane (CH₂F₂), trifluoromethane (CHF₃),other suitable etchants, or combinations thereof.

As shown in FIG. 5 , portions of the target layer 12 are exposed wherethe first region 31 of the hard mask 14 has been removed. Remaining onthe target layer 12 are the portions of the hard mask 14 that make upthe line-end extension regions 32 and the non-bombarded region 33.During the removal of the first region 31 of the hard mask 14, athickness of the line-end extension regions 32 may be reduced. Forexample, an etchant gas utilized to remove the first region 31 of thehard mask 14 may also remove portions of the line-end extension regions32, thereby reducing the thickness or height of the line-end extensionregions 32. However, as previously discussed herein, the line-endextension regions 32 are etched at a lower rate than the first region 31of the hard mask 14, since the line-end extension regions 32 received alower percentage or proportion of ions 20 during the ion bombardment(see FIG. 2 ). Accordingly, the line-end extension regions 32 are etchedat a slower or lower rate than the first region 31. Thus, the thicknessof the line-end extension regions 32 may be reduced during the etching;however, the surface area of the line-end extension regions 32 mayremain substantially the same.

The non-bombarded region 33 may retain substantially the same dimensionsafter the removal of the hard mask 14 as before. For example, since thenon-bombarded region 33 was protected from the bombardment of ions 20,the etching rate of the non-bombarded region 33 of the hard mask 14 wasnot reduced. Accordingly, the use of an etchant to remove the firstregion 31 of the hard mask 14 does not substantially affect thenon-bombarded region 33. However, it will be appreciated that in variousembodiments, the removal of the first region 31 of the hard mask 14 by,for example, an etchant gas may cause some reduction of the thickness ofthe non-bombarded region 33.

As shown in FIG. 6 , the target layer 12 is patterned by transferringthe pattern of the remaining hard mask 14 (e.g., the non-bombardedregion 33 and the line-end extension regions 32) to the target layer 12.The target layer 12 is patterned, for example, by removing portions ofthe target layer 12 that are exposed or otherwise are not covered by thenon-bombarded region 33 or the line-end extension regions 32 of the hardmask 14. The exposed portions of the target layer 12 may be removed byany suitable technique, including, for example, by wet etching, dryetching, RIE, ashing, or any other suitable etching methods. In someembodiments, the exposed portions of the target layer 12 are removed bya second etchant gas 52 having an etchant chemistry with a highselectivity to the target region 12. The second etchant gas 52 may beutilized, for example, to remove the exposed portions of the targetregion 12 while retaining the line-end extension regions 32 and thenon-bombarded region 33 of the hard mask 14. In some embodiments, thesecond etchant gas 52 is different from the first etchant gas 42 whichmay be used to remove the first region 31 of the hard mask 14 (see FIG.4 ). The second etchant gas 52 may be selected as desired, depending,for example, on design considerations. In some embodiments, the secondetchant gas 52 may be selected depending on a composition of the targetlayer 12. For example, a different etchant gas may be used to remove atarget layer formed of a dielectric material than is used to remove atarget layer formed of an electrically conductive material.

As shown in FIG. 7 , a patterned feature 112 is formed from thepatterning of the target layer 12. The patterned feature 112 remains onthe substrate 10 after the exposed portions of the target layer 12 areremoved, for example, as shown and described with respect to FIG. 6 .The patterned feature 112 has a substantially same dimension as thenon-bombarded region 33 and the line-end extension regions 32. Forexample, the patterned feature 112 may have a substantially same lengthand width as the non-bombarded region 33 and the line-end extensionregions 32.

As shown in FIG. 8 , the non-bombarded region 33 and the line-endextension regions 32 of the hard mask 14 may be removed. Thenon-bombarded region 33 and the line-end extension regions 32 of thehard mask 14 may be removed by any suitable technique, including, forexample, by wet etching, dry etching, RIE, ashing, or any other suitableetching methods. In some embodiments, the non-bombarded region 33 andthe line-end extension regions 32 of the hard mask 14 is removed by athird etchant gas having an etchant chemistry with a high selectivity tothe hard mask 14. In some embodiments, the non-bombarded region 33 andthe line-end extension regions 32 of the hard mask 14 are removed by anetchant gas including carbon tetrafluoride (CF₄), difluoromethane(CH₂F₂), trifluoromethane (CHF₃), other suitable etchants, orcombinations thereof. In some embodiments, the third etchant gas is thesame as the first etchant gas 42.

The patterned feature 112 may be any feature of an integrated circuit,including any electrically conductive feature or semiconductor feature.In some embodiments, the patterned feature 112 may be a semiconductorfin of a FinFET device, a gate feature such as a polysilicon or metalgate, an electrically conductive trace or via, or any other feature ofan integrated circuit.

The patterned feature 112 may be formed to have any desired shape. Forexample, while the patterned feature 112 is shown as a linear shapehaving a length along one direction, it will be readily appreciated thatother shapes may be formed in various embodiments using the methodsdescribed herein. For example, the photoresist may be patterned to haveany desired shape utilizing photolithographic techniques describedherein, and the hard mask layer may be subjected to ion implantation asdescribed herein to form line-end extensions at line-ends of thephotoresist having any desired shape.

In some embodiments, multiple patterned features 112 may be formed inclose proximity to one another. The line-end extensions formed by ionimplantation as described herein facilitates a reduction in the gapsbetween adjacent or facing line-ends of features of an integratedcircuit.

FIG. 9 is a cross-sectional diagram illustrating a patterned feature 212in accordance with some embodiments of the present disclosure. Thepatterned feature 212 may be formed by substantially the same method asillustrated in FIGS. 1 through 8 , however with some modifications. Thepatterned feature 212 may be formed by performing the method illustratedin FIGS. 1 through 7 , with a modification with respect to FIG. 8 .

In particular, as shown in FIG. 9 , the non-bombarded region 33 and theline-end extension regions 32 of the hard mask 14 may be removed by anetchant gas that is different from the third etchant gas described withrespect to FIG. 8 . For example, rather than using the third etchant gashaving an etchant chemistry with a high selectivity to the hard mask 14,in embodiments illustrated in FIG. 9 , the non-bombarded region 33 andthe line-end extension regions 32 of the hard mask 14 may be removed bya fourth etchant gas having low or marginal selectivity between the hardmask 14 and the material of the target layer 12.

As the fourth etchant gas has a low or marginal selectivity between thehard mask 14 and the material of the target layer 12, the fourth etchantgas may remove respective portions of the hard mask 14 and the targetlayer 12 at a similar or substantially same rate. Therefore, the thinnerportions of the hard mask 14 (e.g., the line-end extension regions 32)may be fully removed by the etchant gas before the thicker portions ofthe hard mask 14 (e.g., the non-bombarded region 33) is fully removed.The removal of the line-end extension regions (second regions 32) priorto complete removal of the non-bombarded regions 33 thus exposesportions of the target layer 12 in the regions where the line-endextension regions (second regions 32) are first removed. Accordingly,the resultant shape of the patterned feature 212 may resemble the shapeof the hard mask 14 as shown, for example, at FIG. 7 . For example, thepatterned feature 212 may have a first portion 201 that is thicker thansecond portions 202 which extend laterally outward from the firstportion 201. The first portion 201 of the patterned feature 212 may bereferred to as a “nature line-end” as the first portion 201 hasdimensions (e.g., a length and width) corresponding to dimensions of thephotoresist 16 (see FIG. 2 ) and the non-bombarded region 33 of the hardmask 14. The second portions 202 of the patterned feature 212 may bereferred to as “extended line-end” portions as the second portions 202have dimensions corresponding to the line-end extension regions (secondregions 32) of the hard mask 14.

FIG. 10 is a plan view diagram illustrating a device 300, which may bemanufactured in accordance with the method illustrated herein, forexample, with reference to FIGS. 1 through 9 . The device 300 may be anelectronic device, for example, an integrated circuit or the like.

The device 300 includes a plurality of patterned features 312 formed ona substrate 310. The patterned features 312 may be formed according tothe methods described herein, for example, as described with respect toFIGS. 1 through 9 . In various embodiments, the patterned features 312may include, for example, semiconductor device features, such as finsfor a FinFET device, gate features, conductive traces or vias, or anyother features of an integrated circuit.

At least some of the patterned features 312 may include nature line endportions 312 a, 312 b and line-end extension portions 332 a, 332 b. Theline-end extension portions 332 a, 332 b may be formed, for example, byion bombardment as described previously herein. The nature line endportions 312 a, 312 b represent portions of the patterned features 312that are blocked by the ion bombardment, for example, as describedpreviously herein with regard to the non-bombarded regions 33. Utilizingprocesses described herein, such as ion bombardment, the line-endextension portions 332 a, 332 b may be formed in a way that facilitatesa reduction of an end-to-end gap between the patterned features 312.

In some embodiments, the plurality of patterned features 312 may beformed based on a layout that includes a layout of shapes. The layoutmay be, for example, a data file stored on a non-transitorycomputer-readable medium and represented in a design standard such asGDSII, OASIS, or the like. The layout may be a digital representation ofthe device 300, which may be an integrated circuit. The shapes of thelayout may correspond to and define physical features of the device 300.More particularly, the shapes of the layout may define physicalfeatures, such as portions of the patterned features 312 of the device300. However, the layout may be constrained by dimensional limitationsof photolithographic processes for manufacturing an integrated circuitbased on the layout. For example, gaps (or line end to end distances)between the shapes of the layout may be constrained by dimensions of aphotomask that can be physically produced based on the layout. Moreparticularly, a nature line end-to-end gap G1 between facing shapes ofthe layout may be confined by photolithographic processes, such asdimensional limitations of the photomask that can be produced to formthe shapes.

In some embodiments, a photomask is formed based on the shapes of thelayout. As described, for example, with respect to FIGS. 1 and 2 , ahard mask layer is formed on a target layer, and the photomask may beused to pattern a photoresist formed over the hard mask layer. Thepatterned photoresist may correspond with the patterned features 312 andthe patterned features 312 a and 312 b shown in FIG. 10 , and a minimumdistance between the patterned photoresist (e.g., for forming thefeatures 312 a and 312 b) may be the nature line end-to-end gap G1.Line-end extension regions 332 a, 332 b of the patterned features 312 a,312 b may be uncovered by the photoresist, and the line-end extensionregions 332 a, 332 b may be formed as previously described herein, e.g.,by ion bombardment to form line-end extension regions in the hard mask,and subsequently patterning a target layer to form the patternedfeatures 312 including the line-end extension regions 332 a, 332 b.

Utilizing processes described herein, such as ion bombardment to formline-end extension regions, the line-end extension portions 332 a, 332 bof the patterned features 312 may be formed with a reduced lineend-to-end gap G2 between the patterned features 312, as compared to thenature line end-to-end gap G1 which is limited by limitations oftraditional photolithographic processes.

In some embodiments, the line end-to-end gap G2 may be less than 25 nm.In some embodiments, the line end-to-end gap G2 may be less than 18 nm.In some embodiments, the line end-to-end gap G2 may be less than 14 nm.In some embodiments, the line end-to-end gap G2 may be less than 10 nm.In some embodiments, the line end-to-end gap G2 may be within a rangefrom about 5 nm to about 25 nm. By forming the line end-to-end gap G2within this range, the line ends of patterned features 312 may be formedvery close to one another, thereby increasing a number of such features312 that may be formed within a given area, while having a sufficientgap or distance between the features 312 to electrically isolate thefeatures 312 from one another and prevent or reduce undesirable crosscoupling of the features 312.

The dimensions of the line end-to-end gap G2 is not limited by anyparticular dimensional limitations of photolithographic or cutprocesses, but instead, the gap G2 may be formed having a significantlyreduced distance that is limited by the height h of the photoresist andthe ion beam angle θ (as described, for example, with respect to FIG. 2), each of which may be selected as desired to provide a desired lengthof the line-end extension regions, as well as a desired gap G2 betweenthe patterned features 312.

As previously discussed, the patterned features 312 may be any featuresof an integrated circuit, including, for example, semiconductor devicefeatures, such as fins for a FinFET device, gate features, conductivetraces or vias, or any other features of an integrated circuit.

It will be readily appreciated the device 300 shown in FIG. 10 may be aportion or region of an integrated circuit, and in some embodiments, thedevice 300 may include a variety of additional features, including, forexample, additional patterned features 312, as well as any otherfeatures of an integrated circuit.

The present disclosure provides, in various embodiments, methods anddevices in which line-end extensions of patterned features are formed atthe ends of feature lines, thereby facilitating a reduction in thedistance or gap that may be achieved between patterned features of anintegrated circuit. In some embodiments, the line-end extensions may beformed without additional cut layers (and corresponding additional maskprocesses), which otherwise may be relied on to form line-end extensionsin other techniques. This provides a significant advantage in terms ofincreasing density of features which may be formed in an integratedcircuit.

According to one embodiment, a method includes forming a patternedphotoresist on a first region of a hard mask layer. A line-end extensionregion is formed in the hard mask layer. The line-end extension regionextends laterally outward from an end of the first region of the hardmask layer. The line-end extension region may be formed by changing aphysical property of the hard mask layer at the line-end extensionregion.

According to another embodiment, a method is provided that includesforming a hard mask layer on a target layer. The target layer isdisposed between a substrate and the hard mask layer. A patternedphotoresist is formed on a plurality of first regions of the hard masklayer. A plurality of line-end extension regions is formed extendingoutwardly from ends of the plurality of first regions by irradiating thehard mask layer with a plurality of ion beams. Each of the ion beamshave a non-zero ion beam angle with respect to a direction orthogonal tothe hard mask layer, and the patterned photoresist blocks at least aportion of the plurality of ion beams from reaching the plurality ofline-end extension regions. The patterned photoresist is removed.Portions of the target layer are exposed by removing portions of thehard mask layer outside of the plurality of first regions and theplurality of line-end extension regions. A patterned feature is formedin the target layer by removing the exposed portions of the targetlayer.

According to yet another embodiment, an integrated circuit includes asubstrate and a plurality of patterned features on the substrate. Eachof the patterned features is formed of a same material. A distancebetween an end of a first patterned feature of the plurality of featuresand an end of a second patterned feature of the plurality of patternedfeatures is less than 25 nm.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

The various embodiments described above can be combined to providefurther embodiments. These and other changes can be made to theembodiments in light of the above-detailed description. In general, inthe following claims, the terms used should not be construed to limitthe claims to the specific embodiments disclosed in the specificationand the claims, but should be construed to include all possibleembodiments along with the full scope of equivalents to which suchclaims are entitled. Accordingly, the claims are not limited by thedisclosure.

The invention claimed is:
 1. A method, comprising: forming a patternedphotoresist on a first region of a hard mask layer; and forming aline-end extension region in the hard mask layer, the line-end extensionregion extending laterally outward from an end of the first region ofthe hard mask layer, the forming the line-end extension region includingchanging a physical property of the hard mask layer at the line-endextension region; removing the patterned photoresist; and removingportions of the hard mask layer outside of the first region and theline-end extension region, thereby exposing portions of a target layer,the removing portions of the hard mask layer outside the first regionand the line-end extension region reducing a thickness of the line-endextension region relative to a thickness of the first region of the hardmask layer.
 2. The method of claim 1, wherein the physical property ofthe hard mask layer includes a selectivity to an etchant gas, whereinthe removing the portions of the hard mask layer includes removing theportions of the hard mask layer by etching the portions of the hard masklayer with the etchant gas.
 3. The method of claim 1, furthercomprising: removing the exposed portions of the target layer.
 4. Themethod of claim 3, further comprising: removing the first region and theline-end extension region of the hard mask layer.
 5. The method of claim1, wherein the forming the line-end extension region includes:implanting a first concentration of ions in the line-end extensionregion of the hard mask layer; and implanting a second concentration ofions in the hard mask layer outside of the line-end extension region,the second concentration of ions being greater than the firstconcentration of ions.
 6. The method of claim 1, wherein the forming theline-end extension region in the hard mask layer includes irradiatingthe hard mask layer with an ion beam, the ion beam having a non-zero ionbeam angle with respect to a direction orthogonal to the hard masklayer.
 7. The method of claim 6, wherein the non-zero ion beam angle isless than about 85°.
 8. The method of claim 6, wherein the non-zero ionbeam angle is greater than 30°.
 9. The method of claim 6, wherein thenon-zero ion beam angle is within a range from about 50° to about 80°.10. The method of claim 6, wherein the ion beam includes ions formed ofan element selected from the group including: nitrogen (N), tellurium(Te), boron (B), gallium (Ga), phosphorus (P), arsenic (As), argon (Ar),krypton (Kr), and xenon (Xe).
 11. The method of claim 1, wherein alength of the line-end extension region is based at least partly on aheight of the patterned photoresist.
 12. The method of claim 11, whereinthe height of the patterned photoresist is within a range from about 20nm to about 50 nm.
 13. The method of claim 1, wherein the first regionof the hard mask includes a length and an end and forming a line-endextension region in the hard mask layer includes forming a lineextension region in the hard mask that extends laterally outward fromthe end of the length of the first region of the hard mask.
 14. Amethod, comprising: forming a hard mask layer on a target layer, thetarget layer disposed between a substrate and the hard mask layer;forming a patterned photoresist on a plurality of first regions of thehard mask layer; forming a plurality of line-end extension regionsextending outwardly from ends of the plurality of first regions byirradiating the hard mask layer with a plurality of ion beams eachhaving a non-zero ion beam angle with respect to a direction orthogonalto the hard mask layer, the patterned photoresist blocking at least aportion of the plurality of ion beams from reaching the plurality ofline-end extension regions; removing the patterned photoresist; exposingportions of the target layer by removing portions of the hard mask layeroutside of the plurality of first regions and the plurality of line-endextension regions, the removing portions of the hard mask layer outsidethe plurality of first regions and the plurality of line-end extensionregions reducing a thickness of the plurality of line-end extensionregions relative to a thickness of the plurality of first regions of thehard mask layer; and forming a patterned feature in the target layer byremoving the exposed portions of the target layer.
 15. The method ofclaim 14, wherein the forming the plurality of line-end extensionregions includes changing, by the irradiating the hard mask layer, aselectivity to an etchant gas in the plurality of line-end extensionregions of the hard mask layer.
 16. The method of claim 15, wherein theremoving portions of the hard mask layer outside of the plurality offirst regions and the plurality of line-end extension regions includesexposing the hard mask layer to the etchant gas, the etchant gas havinga lower selectivity to the plurality of line-end extension regions thanto the portions of the hard mask layer outside of the plurality of firstregions and the plurality of line-end extension regions.
 17. The methodof claim 15, wherein the forming the plurality of line-end extensionregions includes forming the plurality of line-end extension regions tohave a length substantially equal to h×tan θ, wherein h is a height ofthe patterned photoresist and θ is the non-zero ion beam angle.
 18. Themethod of claim 14, wherein each of the plurality of first regions ofthe hard mask layer includes a length and an end and forming a pluralityof line-end extension regions includes forming a plurality of lineextension regions in the hard mask each of which extends laterallyoutward from the respective end of the length of the first regions ofthe hard mask and parallel to the length of the first region.
 19. Amethod, comprising: forming a patterned photoresist on a first region ofa hard mask layer, the first region extending for a length andterminating at an end; and forming a line-end extension region in thehard mask layer, the line-end extension region extending laterallyoutward from the end of the first region of the hard mask layer, theforming the line-end extension region including changing a physicalproperty of the hard mask layer at the line-end extension region;removing the patterned photoresist; and removing portions of the hardmask layer outside of the first region and the line-end extensionregion, thereby exposing portions of a target layer, the removingportions of the hard mask layer outside the first region and theline-end extension region reducing a thickness of the line-end extensionregion relative to a thickness of the first region of the hard masklayer.
 20. The method of claim 19, wherein the forming a line-endextension region in the hard mask layer includes forming a lineextension region in the hard mask that extends laterally outward fromthe end of the length of the first region of the hard mask and parallelto the length of the first region.